The compound dodecahydro-3a,6,6,9a-tetramethylnaphtho[2,1-b]furan (hereinafter Naphthofuran II) is a synthetic congener of Ambergris, a rare perfumery composition of natural origin having a sweet, woody, amber bouquet. Naphthofuran II has been used in perfume compositions and in cleaning formulations, and as a fragrance for toiletries and household products where a persistent amber effect is desired. Naphthofuran II is also a component of tincture of Ambergris and synthetic Naphthofuran II has been used in artificial Ambergris formulations.
Naphthofuran II may be produced synthetically from 3-ethenyldecahydro-2-hydroxy-2,5,5,8a-pentamethyl-1-naphthalenepropanol, commonly known as sclareol. One method for this conversion is a two stage oxidation followed by a hydride reduction and cyclization. See, for example, U.S. Pat. No. 3,050,532; U.S. Pat. No. 3,029,255; and Aust. J. Chem., 1971, 24, 591. Another method involves oxidation of sclareol to sclareol oxide followed by a multi-step synthesis to produce Naphthofuran II as a mixture of stereoisomers, as described in Helv. Chim. Acta, 1942, 25 621; J. Chem. Soc., 1960, 4613; Helv. Chim. Acta, 1950, 33 1251; U.S. Pat. No. 3,029,255, 1962; Helv. Chim. Acta, 1950, 33 1308; J. Am. Chem. Soc., 1963, 85 3979); and Helv. Chim. Acta, 1951, 34 1664.
These methods, however, lack simplicity and are based upon multiple synthetic reactions. Moreover, they produce undesirable side reactions and do not generate high yields of Naphthofuran II. Accordingly, it is an object of the invention to develop a simple method for the production of Naphthofuran II for sclareol. Another object is the production of a high yield of Naphthofuran II without the complications caused by side reactions.